Enclosures having an improved tactile surface

ABSTRACT

Embodiments of an electronic device comprising an enclosure and electrical components disposed at least partially inside the enclosure, wherein the enclosure comprises a substrate having a tactile surface are disclosed. The tactile surface may include a textured surface, a coated surface or a coated textured surface that exhibits a low fingerprint visibility, when a fingerprint is applied to the tactile surface. In one or more embodiments, the substrate exhibits an average transmittance of about 80% or greater over the visible spectrum, a coefficient of friction less than about 0.3, a surface roughness Ra of about 500 nm or greater, and either one or both a transmission haze greater than about 60%, and a reflection haze at either 2 degrees from specular or 5 degrees from specular greater than 60%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application and claims the benefit ofpriority under 35 U.S.C. § 120 of U.S. application Ser. No. 15/407,964filed on Jan. 17, 2017, which in turn, claims the benefit of priorityunder 35 U.S.C. § 119 of U.S. Provisional Application Ser. No.62/383,888 filed on Sep. 6, 2016 and U.S. Provisional Application Ser.No. 62/279,893 filed on Jan. 18, 2016, the contents of each of which arerelied upon and incorporated herein by reference in their entireties.

TECHNICAL FIELD

This disclosure relates to enclosures for electronic devices and moreparticularly to enclosures including an improved tactile surface thatpermits transmission of wireless data transmission or wireless chargingenergy therethrough.

BACKGROUND

As portable electronic devices such as laptops, tablets, media players,and mobile phones have become smaller, lighter in weight and morepowerful, the design of some components and enclosures of the portablecomputing devices must be improved. This design of such enclosuresshould be lighter in weight and thinner, but strong and rigid. Thelighter weight enclosures, which typically use thin plastic structuresand few fasteners, tend to be more flexible, are prone to scratching,and have a greater tendency to buckle and bow as opposed to stronger andmore rigid enclosures which typically use thicker plastic structures andmore fasteners which are thicker and have more weight. The increasedweight of the stronger and more rigid structures may lead to userdissatisfaction, and bowing/buckling of the lighter weight structuresmay damage the internal parts of the portable electronic devices.

From an aesthetic standpoint, surfaces which exhibit an improved tactilesurface or feel and which are also resistant to the transfer or smudgingof fingerprints are desired in enclosures. For applications related toelectronic devices, the general requirements for such surfaces includehigh transmission, controlled haze, resistance to fingerprint transfer,and robustness to handling. A fingerprint-resistant surface must beresistant to both water and oil transfer when touched by a finger orskin of a user.

In view of the foregoing problems with existing enclosures, there is aneed for improved enclosures for portable electronic devices. Inparticular, there is a need for enclosures that are more cost effective,smaller, lighter, stronger and aesthetically more pleasing than currentenclosure designs.

SUMMARY

A first aspect of this disclosure pertains to an electronic devicecomprising an enclosure; and electrical components disposed at leastpartially inside the enclosure and including at least a controller, amemory, and a display. In one or more embodiments, the enclosurecomprises a substrate that exhibits an average transmittance of about80% or greater over the visible spectrum. In some instances, thesubstrate exhibits a kinetic coefficient of friction (COF) less thanabout 0.3, when measured using the COF Test Method, as described herein.In some instances, the substrate exhibits a static coefficient offriction (COF) less than about 0.3, when measured using the COF TestMethod. In some instances, the substrate comprises a surface having asurface roughness Ra of about 500 nm or greater or about 900 nm orgreater. In one or more embodiments, the substrate exhibits a either oneor both a transmission haze greater than about 60%, and a reflectionhaze at either 2 degrees from specular or 5 degrees from speculargreater than 60%. The transmittance haze and/or the specular haze may beabout 90% or greater.

In some embodiments, the substrate may be described as glass-based. Insome embodiments, the substrate comprises an amorphous substrate or acrystalline substrate. Embodiments including an amorphous substrate mayinclude any one of a soda lime glass, an alkali aluminosilicate glass,an alkali containing borosilicate glass and an alkalialuminoborosilicate glass. The amorphous substrate of some embodimentsmay be strengthened and may include any one or more of a compressivesurface layer having a depth of compressive layer (DOC) greater than orequal to 20 μm, a compressive stress greater than 400 MPa, and a centraltension of more than 20 MPa. In some embodiments, the substrate is acrystalline substrate comprises a strengthened glass ceramic substrate,a non-strengthened glass-ceramic, or a single crystal substrates.

The substrate may include an ink layer, a hydrophobic material, anoleophobic material or a material that exhibits both hydrophobicity andoleophobicity, disposed a major surface of the substrate. In someoptions, the substrate may include a colored glass.

In some embodiments, the substrate may include a plurality of surfacefeatures having a longest cross-sectional dimension in the range fromabout 10 micrometers to about 100 micrometers (or from about 10micrometers to about 50 micrometers). In some embodiments, the pluralityof features has an average longest cross-sectional dimension that isabout 2 times or less than the longest cross-sectional dimension.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view of an electronic device according to one or moreembodiments;

FIG. 2 is a perspective view of the electronic device of FIG. 1;

FIG. 3 is a side view of an enclosure according to one or moreembodiments;

FIG. 4 is a graph showing the correlation of transmittance haze of anarticle including a tactile surface on a single surface or on opposingsurfaces, based on Examples 1 and 2;

FIG. 5 is a schematic illustration of the COF Test Method;

FIG. 6 is an optical microscope image of Example 1K;

FIGS. 7A-7E are graphs showing the impact of easy-to-clean (ETC) coatingon COF for the different haze and roughness levels of Examples 2A-2E;and

FIG. 8 is a graph showing the static COF of Examples 2B-2E as a functionof transmittance haze.

DETAILED DESCRIPTION

As is described herein below, there is a need for more cost effective,smaller, lighter, stronger and aesthetically more pleasing enclosuresfor portable electronic devices. Such devices may include mobile phones,media (including music) players, laptop or notebook computers, tablets,gaming devices, electronic book readers and other devices. Embodimentsof this disclosure pertain to suitable materials for such enclosures,which exhibit weight and/or resistance to impact damage (e.g., denting)and include an improved tactile surface. Unlike many of the knownmaterials used for enclosures, in particular metallic enclosures, thematerials described herein do not interfere with wirelesscommunications. For example, the enclosure may permit transmission ofradio frequency, microwaves, magnetic fields, inductive fields, wirelessdata transmission, wireless charging energy or combinations thereof.Some embodiments of this disclosure pertain to electronic devicesincluding the enclosures described herein.

A first aspect of this disclosure pertains to an electronic deviceincluding an embodiment of the enclosures described herein, and isillustrated in FIGS. 1-2. The electronic device 1000 includes anenclosure 1020 having a front surface 1040, a back surface 1060, andside surfaces 1080; and electrical components (not shown) that are atleast partially inside or entirely within the enclosure. The electroniccomponents include at least a controller, a memory, and a display 1120,which may be at or adjacent to the front surface of the enclosure. Thedisplay 1120 may be present on the side surfaces 1080 and/or the backsurface 1060. In the embodiment shown in FIGS. 1 and 2, a cover glass100 is disposed over the display 1120. In one or more embodiments, theenclosure includes a substrate including a tactile surface, as will bedescribed herein. As used herein the terms “enclosure” maybe usedinterchangeably with “housing” and “protective cover”.

As shown in FIG. 3, the enclosure 100 may include a substrate 101, whichforms the entirety of the enclosure. In some embodiments, the substratemay form a portion of the enclosure. As shown in FIG. 3, the substrateincludes opposing major surfaces, 110, 120 and opposing minor surfaces130, 140, though other configurations are possible. In some embodiments,the enclosure covers non-display areas or components of an electronicdevice. Such enclosures can form a back surface of an electronic deviceand/or any of the edges of the electronic device. In one or moreembodiments, one major surface 120 of the substrate may form an exteriorsurface of the electronic device and the other major surface 110 mayform an interior surface of the enclosure and is adjacent to internalcomponents of the electronic device. The major surface 110 forming theinterior surface may include a coating forming a decorative feature,which may include a coating imparting a color, graphic, metallizedsurface and the like. In some embodiments, only one or both the majorsurfaces may include the tactile surface described herein. In someembodiments, all of the surfaces (110, 120, 130, 140) may include thetactile surface described herein. In some embodiments, the tactilesurface may be present on only the major surface that forms the exteriorsurface of the enclosure.

As used herein, the term “anti-fingerprint” generally relates to areduction in the visibility of fingerprints on a surface. Such reductionmay be achieved by imparting hydrophobicity (i.e., contact angle ofwater>90°) to a surface, oleophilicity (i.e., contact angle of oil<90°)to a surface, and resistance to adherence of particulate or liquidmatter found in fingerprints to a surface, or a combination thereof. Inone or more embodiments, the reduction may be achieved by reducing theCOF of the surface. In some embodiments, these properties may beimparted to a surface by various surface modifications, coatings or acombination thereof.

Substrate

The substrate may be sheet-like in form or may be shaped to have a2.5-dimensional (as shown in FIG. 3) or 3-dimensional shape. In one moreembodiments, the substrate may include an amorphous substrate, acrystalline substrate, or a combination thereof. In some embodiments,the substrate may be characterized as inorganic, or more specifically,glass-based. In one or more embodiments, the amorphous substrate mayinclude a glass substrate, which may be strengthened ornon-strengthened. Examples of suitable glass substrates include sodalime glass substrates, alkali aluminosilicate glass substrates, alkalicontaining borosilicate glass substrates and alkali aluminoborosilicateglass substrates. In some variants, the glass substrates may be free oflithia. In one or more alternative embodiments, the substrate 110 mayinclude crystalline substrates such as glass-ceramic substrates (whichmay be strengthened or non-strengthened) or may include a single crystalstructure, such as sapphire. In one or more specific embodiments, thesubstrate includes an amorphous base (e.g., glass) and a crystallinecladding (e.g., sapphire layer, a polycrystalline alumina layer and/oror a spinel (MgAl₂O₄) layer).

In some embodiments, the substrate 110 may be organic and mayspecifically be polymeric. Examples of suitable polymers include,without limitation: thermoplastics including polystyrene (PS) (includingstyrene copolymers and blends), polycarbonate (PC) (including copolymersand blends), polyesters (including copolymers and blends, includingpolyethyleneterephthalate and polyethyleneterephthalate copolymers),polyolefins (PO) and cyclicpolyolefins (cyclic-PO), polyvinylchloride(PVC), acrylic polymers including polymethyl methacrylate (PMMA)(including copolymers and blends), thermoplastic urethanes (TPU),polyetherimide (PEI) and blends of these polymers with each other. Otherexemplary polymers include epoxy, styrenic, phenolic, melamine, andsilicone resins.

The substrate may be substantially planar, although other embodimentsmay utilize a curved or otherwise shaped or sculpted substrate (e.g.,having a 2.5-dimensional or 3-dimensional shape). The substrate may besubstantially optically clear, transparent and free from lightscattering. The substrate may have a refractive index in the range fromabout 1.45 to about 1.55. As used herein, the refractive index valuesare with respect to a wavelength of 550 nm. The substrate may becharacterized as having a high average flexural strength (when comparedto substrates that are not strengthened, as described herein) or highsurface strain-to-failure (when compared to substrates that are notstrengthened, as described herein) as measured on one or more majoropposing surfaces of such substrates.

In one or more embodiments, the substrate may exhibit a color or may bea colored substrate (i.e., a substrate that appears to have a color orshade. Where glass-based substrates are utilized, the glass-basedsubstrate may include a composition with a colorant such as oxides ofcobalt, vanadium, copper, iron, manganese and the like.

Additionally or alternatively, the thickness of the substrate may varyalong one or more of its dimensions for aesthetic and/or functionalreasons. For example, the edges of the substrate may be thicker ascompared to more central regions of the substrate. The length, width andthickness dimensions of the substrate may also vary according to theenclosure application or use.

The substrate may be provided using a variety of different processes.For instance, where the substrate includes a glass substrate, exemplaryglass substrate forming methods include float glass processes anddown-draw processes such as fusion draw and slot draw.

A glass substrate prepared by a float glass process may be characterizedby smooth surfaces and uniform thickness is made by floating moltenglass on a bed of molten metal, typically tin. In an example process,molten glass that is fed onto the surface of the molten tin bed forms afloating glass ribbon. As the glass ribbon flows along the tin bath, thetemperature is gradually decreased until the glass ribbon solidifiesinto a solid glass substrate that can be lifted from the tin ontorollers. Once off the bath, the glass substrate can be cooled furtherand annealed to reduce internal stress.

Down-draw processes produce glass substrates having a uniform thicknessthat possess relatively pristine surfaces. Because the average flexuralstrength of the glass substrate is controlled by the amount and size ofsurface flaws, a pristine surface that has had minimal contact has ahigher initial strength. When this high strength glass substrate is thenfurther strengthened (e.g., chemically), the resultant strength can behigher than that of a glass substrate with a surface that has beenlapped and polished. Down-drawn glass substrates may be drawn to athickness of less than about 2 mm. In addition, down drawn glasssubstrates have a very flat, smooth surface that can be used in itsfinal application without costly grinding and polishing.

The fusion draw process, for example, uses a drawing tank that has achannel for accepting molten glass raw material. The channel has weirsthat are open at the top along the length of the channel on both sidesof the channel. When the channel fills with molten material, the moltenglass overflows the weirs. Due to gravity, the molten glass flows downthe outside surfaces of the drawing tank as two flowing glass films.These outside surfaces of the drawing tank extend down and inwardly sothat they join at an edge below the drawing tank. The two flowing glassfilms join at this edge to fuse and form a single flowing glasssubstrate. The fusion draw method offers the advantage that, because thetwo glass films flowing over the channel fuse together, neither of theoutside surfaces of the resulting glass substrate comes in contact withany part of the apparatus. Thus, the surface properties of the fusiondrawn glass substrate are not affected by such contact.

The slot draw process is distinct from the fusion draw method. In slotdraw processes, the molten raw material glass is provided to a drawingtank. The bottom of the drawing tank has an open slot with a nozzle thatextends the length of the slot. The molten glass flows through theslot/nozzle and is drawn downward as a continuous substrate and into anannealing region.

In some embodiments, the compositions used for the glass substrate maybe batched with 0-2 mol. % of at least one fining agent selected from agroup that includes Na₂SO₄, NaCl, NaF, NaBr, K₂SO₄, KCl, KF, KBr, andSnO₂.

Once formed, a glass substrate may be strengthened to form astrengthened glass substrate. It should be noted that glass ceramicsubstrates may also be strengthened in the same manner as glasssubstrates. As used herein, the term “strengthened substrate” may referto a glass substrate or a glass ceramic substrates that has beenchemically strengthened, for example through ion-exchange of larger ionsfor smaller ions in the surface of the glass or glass ceramic substrate.However, other strengthening methods known in the art, such as thermaltempering, may be utilized to form strengthened glass substrates.

The strengthened substrates described herein may be chemicallystrengthened by an ion exchange process. In the ion-exchange process,typically by immersion of a glass or glass ceramic substrate into amolten salt bath for a predetermined period of time, ions at or near thesurface(s) of the glass or glass ceramic substrate are exchanged forlarger metal ions from the salt bath. In one embodiment, the temperatureof the molten salt bath is about 400-430° C. and the predetermined timeperiod is about four to about eight hours. The incorporation of thelarger ions into the glass or glass ceramic substrate strengthens thesubstrate by creating a compressive stress in a near surface region orin regions at and adjacent to the surface(s) of the substrate. Acorresponding tensile stress is induced within a central region orregions at a distance from the surface(s) of the substrate to balancethe compressive stress. Glass or glass ceramic substrates utilizing thisstrengthening process may be described more specifically aschemically-strengthened or ion-exchanged glass or glass ceramicsubstrates.

In one example, sodium ions in a strengthened glass or glass ceramicsubstrate are replaced by potassium ions from the molten bath, such as apotassium nitrate salt bath, though other alkali metal ions havinglarger atomic radii, such as rubidium or cesium, can replace smalleralkali metal ions in the glass. According to particular embodiments,smaller alkali metal ions in the glass or glass ceramic can be replacedby Ag+ ions. Similarly, other alkali metal salts such as, but notlimited to, sulfates, phosphates, halides, and the like may be used inthe ion exchange process.

The replacement of smaller ions by larger ions at a temperature belowthat at which the glass network can relax produces a distribution ofions across the surface(s) of the strengthened substrate that results ina stress profile. The larger volume of the incoming ion produces acompressive stress (CS) on the surface and tension (central tension, orCT) in the center of the strengthened substrate. Depth of exchange maybe described as the depth within the strengthened glass or glass ceramicsubstrate (i.e., the distance from a surface of the glass substrate to acentral region of the glass or glass ceramic substrate), at which ionexchange facilitated by the ion exchange process takes place. Maximum CTvalues are measured using a scattered light polariscope (SCALP)technique as known in the art.

Compressive stress (including surface CS) is measured by surface stressmeter (FSM) using commercially available instruments such as theFSM-6000, manufactured by Orihara Industrial Co., Ltd. (Japan). Surfacestress measurements rely upon the accurate measurement of the stressoptical coefficient (SOC), which is related to the birefringence of theglass. SOC in turn is measured according to Procedure C (Glass DiscMethod) described in ASTM standard C770-16, entitled “Standard TestMethod for Measurement of Glass Stress-Optical Coefficient,” thecontents of which are incorporated herein by reference in theirentirety.

As used herein, DOC means the depth at which the stress in thechemically strengthened alkali aluminosilicate glass article describedherein changes from compressive to tensile. DOC may be measured by FSMor SCALP depending on the ion exchange treatment. Where the stress inthe glass article is generated by exchanging potassium ions into theglass article, FSM is used to measure DOC. Where the stress is generatedby exchanging sodium ions into the glass article, SCALP is used tomeasure DOC. Where the stress in the glass article is generated byexchanging both potassium and sodium ions into the glass, the DOC ismeasured by SCALP, since it is believed the exchange depth of sodiumindicates the DOC and the exchange depth of potassium ions indicates achange in the magnitude of the compressive stress (but not the change instress from compressive to tensile); the exchange depth of potassiumions in such glass articles is measured by FSM.

In one embodiment, a strengthened glass or glass ceramic substrate canhave a surface compressive stress of 300 MPa or greater, e.g., 400 MPaor greater, 450 MPa or greater, 500 MPa or greater, 550 MPa or greater,600 MPa or greater, 650 MPa or greater, 700 MPa or greater, 750 MPa orgreater or 800 MPa or greater. The strengthened glass or glass ceramicsubstrate may have a compressive depth of layer 15 μm or greater, 20 μmor greater (e.g., 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or greater)and/or a central tension of 10 MPa or greater, 20 MPa or greater, 30 MPaor greater, 40 MPa or greater (e.g., 42 MPa, 45 MPa, or 50 MPa orgreater) but less than 100 MPa (e.g., 95, 90, 85, 80, 75, 70, 65, 60, 55MPa or less). In one or more specific embodiments, the strengthenedglass or glass ceramic substrate has one or more of the following: asurface compressive stress greater than 500 MPa, a depth of compressivelayer greater than 15 μm, and a central tension greater than 18 MPa.

Without being bound by theory, it is believed that strengthened glass orglass ceramic substrates with a surface compressive stress greater than500 MPa and a compressive depth of layer greater than about 15 μmtypically have greater strain-to-failure than non-strengthened glass orglass ceramic substrates (or, in other words, glass substrates that havenot been ion exchanged or otherwise strengthened).

Example glasses that may be used in the substrate may include alkalialuminosilicate glass compositions or alkali aluminoborosilicate glasscompositions, though other glass compositions are contemplated. Suchglass compositions may be characterized as ion exchangeable. As usedherein, “ion exchangeable” means that a substrate comprising thecomposition is capable of exchanging cations located at or near thesurface of the substrate with cations of the same valence that areeither larger or smaller in size. One example glass compositioncomprises SiO₂, B₂O₃ and Na₂O, where (SiO₂+B₂O₃)≥66 mol. %, and Na₂O≥9mol. %. In an embodiment, the glass composition includes at least 6 wt.% aluminum oxide. In a further embodiment, the substrate includes aglass composition with one or more alkaline earth oxides, such that acontent of alkaline earth oxides is at least 5 wt. %. Suitable glasscompositions, in some embodiments, further comprise at least one of K₂O,MgO, and CaO. In a particular embodiment, the glass compositions used inthe substrate can comprise 61-75 mol % SiO2; 7-15 mol % Al₂O₃; 0-12 mol% B₂O₃; 9-21 mol % Na₂O; 0-4 mol % K₂O; 0-7 mol % MgO; and 0-3 mol %CaO.

A further example glass composition suitable for the substratecomprises: 60-70 mol % SiO₂; 6-14 mol % Al₂O₃; 0-15 mol % B₂O₃; 0-15 mol% Li₂O; 0-20 mol % Na₂O; 0-10 mol % K₂O; 0-8 mol % MgO; 0-10 mol % CaO;0-5 mol % ZrO₂; 0-1 mol % SnO₂; 0-1 mol % CeO₂; less than 50 ppm As₂O₃;and less than 50 ppm Sb₂O₃; where 12 mol %≤(Li₂O+Na₂O+K₂O)≤20 mol % and0 mol %≤(MgO+CaO)≤10 mol %.

A still further example glass composition suitable for the substratecomprises: 63.5-66.5 mol % SiO₂; 8-12 mol % Al₂O₃; 0-3 mol % B₂O₃; 0-5mol % Li₂O; 8-18 mol % Na₂O; 0-5 mol % K₂O; 1-7 mol % MgO; 0-2.5 mol %CaO; 0-3 mol % ZrO₂; 0.05-0.25 mol % SnO₂; 0.05-0.5 mol % CeO₂; lessthan 50 ppm As₂O₃; and less than 50 ppm Sb₂O₃; where 14 mol%≤(Li₂O+Na₂O+K₂O)≤18 mol % and 2 mol % (MgO+CaO) 7 mol %.

In a particular embodiment, an alkali aluminosilicate glass compositionsuitable for the substrate comprises alumina, at least one alkali metaland, in some embodiments, greater than 50 mol % SiO₂, in otherembodiments at least 58 mol % SiO₂, and in still other embodiments atleast 60 mol % SiO₂, wherein the ratio ((Al₂O₃+B₂O₃)/Σmodifiers)>1,where in the ratio the components are expressed in mol % and themodifiers are alkali metal oxides. This glass composition, in particularembodiments, comprises: 58-72 mol % SiO₂; 9-17 mol % Al₂O₃; 2-12 mol %B₂O₃; 8-16 mol % Na₂O; and 0-4 mol % K₂O, wherein the ratio((Al₂O₃+B₂O₃)/Σmodifiers)>1.

In still another embodiment, the substrate may include an alkalialuminosilicate glass composition comprising: 64-68 mol % SiO₂; 12-16mol % Na₂O; 8-12 mol % Al₂O₃; 0-3 mol % B₂O₃; 2-5 mol % K₂O; 4-6 mol %MgO; and 0-5 mol % CaO, wherein: 66 mol %≤SiO₂+B₂O₃+CaO≤69 mol %;Na₂O+K₂O₃+B₂O₃+MgO+CaO+SrO>10 mol %; 5 mol. %≤MgO+CaO+SrO≤8 mol %;(Na₂O+B₂O₃)—Al₂O₃≤2 mol %; 2 mol % Na₂O—Al₂O₃≤6 mol %; and 4 mol%≤(Na₂O+K₂O)—Al₂O₃≤10 mol %.

In an alternative embodiment, the substrate may comprise an alkalialuminosilicate glass composition comprising: 2 mol % or more of Al₂O₃and/or ZrO₂, or 4 mol % or more of Al₂O₃ and/or ZrO₂.

Where the substrate includes a crystalline substrate, the substrate mayinclude a single crystal, which may include Al₂O₃. Such single crystalsubstrates are referred to as sapphire. Other suitable materials for acrystalline substrate include polycrystalline alumina layer and/or or aspinel (MgAl₂O₄).

Optionally, the crystalline substrate may include a glass ceramicsubstrate, which may be strengthened or non-strengthened. Examples ofsuitable glass ceramics may include Li₂O—Al₂O₃—SiO₂ system (i.e.LAS-System) glass ceramics, MgO—Al₂O₃—SiO₂ System (i.e. MAS-System)glass ceramics, and/or glass ceramics that include a predominant crystalphase including β-quartz solid solution, β-spodumene ss, cordierite, andlithium disilicate. The glass ceramic substrates may be strengthenedusing the glass substrate strengthening processes disclosed herein. Inone or more embodiments, MAS-System glass ceramic substrates may bestrengthened in Li₂SO₄ molten salt, whereby 2Li⁺ for Mg²⁺ exchange canoccur.

The substrate according to one or more embodiments can have a thicknessin the range from about 100 μm to about 5 mm. Example substratethicknesses range from about 100 μm to about 500 μm (e.g., 100, 200,300, 400 or 500 μm). Further example substrate thicknesses range fromabout 500 μm to about 1000 μm (e.g., 500, 600, 700, 800, 900 or 1000μm). The substrate may have a thickness greater than about 1 mm (e.g.,about 2, 3, 4, or 5 mm). In one or more specific embodiments, thesubstrate may have a thickness of 2 mm or less or less than 1 mm. Thesubstrate may be acid polished or otherwise treated to remove or reducethe effect of surface flaws.

Tactile Surface

In one or more embodiments, substrate 101 comprises a tactile surface.In some embodiments, the tactile surface may comprise at least a portionof one or both major surfaces 110, 120 of the substrate 101 or one ormore minor surfaces 130, 140 of the substrate. In some embodiments, thetactile surface may be formed on at least a portion of one, two, threeor all of the surfaces of the substrate. In some instances, the tactilesurface may be formed on all of one or more surfaces of the substrate101. In FIG. 3, the tactile surface 150 is formed on major surface 120.In some embodiments, the tactile surface may be formed in apredetermined design. For example, the enclosure may include a designoccupying a portion of a surface, and the tactile surface may be formedon the surface to cover or be disposed adjacent to the design. Thedesign on the enclosure may be provided by a film disposed on one majorsurface of the substrate and the tactile surface may be formed on theopposite major surface, having the same shape as the design.

The tactile surface may include a textured surface (or surface that hasbeen modified to include a texture), a coating, or a combination thereof(i.e., a coated textured surface). The substrate may exhibit certainproperties as measured on the tactile surface. For example, in one ormore embodiments, the substrate may exhibit a haze as measured at thetactile surface in the range from about 60% to about 120%, from about65% to about 120%, from about 70% to about 120%, from about 75% to about120%, from about 80% to about 120%, from about 90% to about 120%, fromabout 100% to about 120%, from about 100% to about 110%, from about 60%to about 110%, from about 60% to about 100%, from about 60% to about90%, from about 60% to about 80%, or from about 60% to about 70%, Thesubstrate may exhibit a transmittance haze as measured through thetactile surface of about 60% or greater, about 70% or greater, about 80%or greater, about 90% or greater, or about 95% or greater. Thetransmittance haze may be up to about 100%. In one or more embodiments,the substrate may exhibit a transmittance haze as measured through thetactile surface in the range from about 60% to about 100%, from about65% to about 100%, from about 70% to about 100%, from about 75% to about100%, from about 80% to about 100%, from about 90% to about 100%, fromabout 92% to about 100%, from about 93% to about 94%, from about 95% toabout 100%, from about 96% to about 100%, from about 97% to about 100%,from about 98% to about 100%, from about 99% to about 100%, from about60% to about 98%, from about 60% to about 96%, from about 60% to about95%, from about 60% to about 94%, from about 60% to about 92%, fromabout 60% to about 90%, from about 60% to about 85%, or from about 60%to about 80%. In one or more embodiments, the substrate may exhibit areflectance haze (as measured on the tactile surface) of about 60% orgreater, about 70% or greater, about 80% or greater or about 90% orgreater. In some instances, the reflectance haze may be up to about100%. In one or more embodiments, the substrate may exhibit areflectance haze as measured on the tactile surface in the range fromabout 60% to about 100%, from about 65% to about 100%, from about 70% toabout 100%, from about 75% to about 100%, from about 80% to about 100%,from about 90% to about 100%, from about 92% to about 100%, from about93% to about 94%, from about 95% to about 100%, from about 96% to about100%, from about 97% to about 100%, from about 98% to about 100%, fromabout 99% to about 100%, from about 60% to about 98%, from about 60% toabout 96%, from about 60% to about 95%, from about 60% to about 94%,from about 60% to about 92%, from about 60% to about 90%, from about 60%to about 85%, or from about 60% to about 80%. Reflectance haze may bemeasured at 2 degrees from specular or 5 degrees from specular. In someembodiments, haze may be measured according to ASTM E430 using atransparency meter such as the Haze-Gard meter supplied by BYK-GardnerGmbH, of Geretsried, Germany. The transmittance haze described hereinmay be influenced by whether the textures tactile surface is present ona single major surface or both major surfaces. FIG. 4 shows thecorrelation of transmittance haze of the substrate including a tactilesurface only a single surface (typically a single major surface) or onopposing surfaces (typically, opposing major surfaces), based onExamples 1 and 2.

The substrate may exhibit a 20° distinctness of image (DOI) (as measuredon the tactile surface) of about 90 or less (e.g., about 85 or less,about 80 or less, about 60 or less, or about 40 or less). As usedherein, the term “distinctness of image” is defined by method A of ASTMprocedure D5767 (ASTM 5767), entitled “Standard Test Methods forInstrumental Measurements of Distinctness-of-Image Gloss of CoatingSurfaces,” the contents of which are incorporated herein by reference intheir entirety. In accordance with method A of ASTM 5767, substratereflectance factor measurements are made on the anti-glare surface atthe specular viewing angle and at an angle slightly off the specularviewing angle. The values obtained from these measurements are combinedto provide a DOI value. In particular, DOI is calculated according tothe equation

$\begin{matrix}{{{DOI} = {\left\lbrack {1 - \frac{Ros}{Rs}} \right\rbrack \times 100}},} & (3)\end{matrix}$where Ros is the relative reflection intensity average between 0.2° and0.4 away from the specular reflection direction, and Rs is the relativereflection intensity average in the specular direction (between +0.05°and −0.05°, centered around the specular reflection direction). If theinput light source angle is +20° from the sample surface normal (as itis throughout this disclosure), and the surface normal to the sample istaken as 0°, then the measurement of specular reflected light Rs istaken as an average in the range of about −19.95° to −20.05°, and Ros istaken as the average reflected intensity in the range of about −20.2° to−20.4° (or from −19.6° to −19.8°, or an average of both of these tworanges). As used herein, DOI values should be directly interpreted asspecifying a target ratio of Ros/Rs as defined herein. In someembodiments, the anti-glare surface has a reflected scattering profilesuch that >95% of the reflected optical power is contained within a coneof +/−10°, where the cone is centered around the specular reflectiondirection for any input angle.

In one or more embodiments, the substrate may exhibit a gloss at 60° of70% or less (e.g., 65% or less, 50% or less, 40% or less, 30% or less or20% or less), as measured on the tactile surface.

Unless otherwise stated, the DOI and gloss is measured on the tactilesurface in reflected mode (i.e., without taking into account the othersurfaces of the substrate). Transmission haze performance is in terms ofthe entire substrate, since these values are measured in the transmittedmode.

In embodiments that utilize a textured surface to form the tactilesurface, the textured surface may include a plurality of featuresdisposed on the surface that are light-scattering, create a roughness ora combination thereof. The features may be disposed directly on thesurface or indirectly on the surface in a random or non-random manner.Randomly disposed features may provide a smooth touch-feeling when thesurface is contacted or swiped with a finger or skin. Specifically,features imparting a degree of roughness can create a smoothtouch-feeling that facilitates gliding of fingers or other objects overthe surface by limiting the contact area of the finger or object withthe textured surface.

In some embodiments, the plurality of features may exhibit a longestcross-sectional dimension (i.e., the largest feature may have a longestcross-sectional dimension) in the range from about 5 micrometers toabout 100 micrometers. Such dimensions may be found in a sample surfacesection having dimensions of about 0.5 mm by 0.5 mm to capture arepresentative average including a number of typical surface features inthe range from about 10 to about 1000. For example, the features mayhave a longest cross-sectional dimension in the range from about 5micrometers to about 90 micrometers, from about 5 micrometers to about80 micrometers, from about 5 micrometers to about 70 micrometers, fromabout 5 micrometers to about 60 micrometers, from about 5 micrometers toabout 50 micrometers, from about 5 micrometers to about 40 micrometers,from about 5 micrometers to about 30 micrometers, from about 10micrometers to about 100 micrometers, from about 15 micrometers to about100 micrometers, from about 20 micrometers to about 100 micrometers,from about 30 micrometers to about 100 micrometers, or from about 10micrometers to about 50 micrometers. The features may include an averagelongest cross-sectional dimension that is about 2 times or more than thelongest cross-sectional dimension of any one feature. The features mayinclude an average longest cross-sectional dimension that is about 2times or less than the longest cross-sectional dimension of any onefeature. The longest cross-sectional dimension of the features may beevaluated by optical microscope under 200× magnification. To determinethe average longest cross-sectional dimension of the features, ten ofthe largest features are selected over a sample surface section havingdimensions of about 0.5 mm by 0.5 mm, and measured by opticalmicroscope. The average measurement is reported as the average longestcross-sectional dimension of the selected features.

In one or more embodiments, the textured surface may exhibit a RMSroughness height (i.e., in the z-direction) in the range from about 0.02micrometers to about 10 micrometers, from about 0.02 micrometers toabout 8 micrometers, from about 0.02 micrometers to about 6 micrometers,from about 0.02 micrometers to about 4 micrometers, from about 0.05micrometers to about 2 micrometers, from about 0.05 micrometers to about1 micrometer, or from about 0.1 to about 0.8 micrometers. The RMSroughness height is measured using methods known in the art such asatomic force microscopy (AFM), stylus contact profilometry, and opticalinterference profilometry. The RMS roughness as described herein ismeasured over a sample surface section having dimensions of 0.5 mm by0.5 mm.

In some embodiments, the textured surface may exhibit a surfaceroughness Ra measuring the vertical height of the features (e.g., asmeasured in the z-direction by an optical surface profiler, such as the3D Optical Surface Profiler available from Zygo Corporation) in therange from about 500 nm or greater. In some instances, the surface Ramay be in the range from about 500 nm to about 2000 nm, from about 500nm to about 1800 nm, from about 500 nm to about 1600 nm, from about 500nm to about 1500 nm, from about 500 nm to about 1400 nm, from about 500nm to about 1200 nm, from about 500 nm to about 1000 nm, from about 600nm to about 2000 nm, from about 800 nm to about 2000 nm, from about 900nm to about 2000 nm, from about 1000 nm to about 2000 nm, from about1100 nm to about 2000 nm, from about 1200 nm to about 2000 nm, or fromabout 900 nm to about 1300 nm. The surface Ra roughness as describedherein is measured over a sample surface section having dimensions ofabout 0.5 mm by 0.5 mm.

In some embodiments, the textured surface may include a low frequency offeatures, large sized features, or a combination thereof which causefingerprint oils to collect in between the features (i.e., in thevalleys created between the features) of the textured structure.Collection of oils between the features reducing the fraction of thesurface that is covered with oil droplets, thus reducing lightscattering from the fingerprint oils. In such embodiments, the texturedsurface may have an RMS roughness height in the range from about 0.05micrometers to about 1 micrometer over a samples size having dimensionsof about 0.5 mm by 0.5 mm.

In some embodiments, the textured surface may have a RMS roughnessheight that is large enough to significantly reduce transfer offingerprint oils into the valleys of the structure, thus also reducinglight scattering through limiting the fraction of the surface that iscovered with oil droplets. Such textured surfaces may have a RMSroughness height in the range from about 1 micrometer to about 10micrometers over a samples size having dimensions of about 0.5 mm by 0.5mm.

In some embodiments, the textured surface comprises a lateral spatialperiod (i.e., in the x-y in-plane direction) in the range from about 0.1micrometers to about 500 microns, from about 0.1 micrometers to about400 microns, from about 0.1 micrometers to about 300 microns, from about0.1 micrometers to about 200 microns, from about 0.1 micrometers toabout 100 microns, from about 0.1 micrometers to about 50 microns, fromabout 0.1 micrometers to about 10 microns, from about 0.5 micrometers toabout 500 microns, from about 1 micrometer to about 500 microns, fromabout 10 micrometers to about 500 microns, from about 50 micrometers toabout 500 microns, from about 100 micrometers to about 500 microns, fromabout 1 micrometer to about 100 micrometers, or from about 10micrometers to about 50 micrometers. Such lateral special period rangesare measured over a samples size having dimensions of about 1 mm by 1mm.

These roughness parameters and surface profiles can be measured usingknown techniques such as atomic force microscopy (AFM), stylus contactsurface profilometry, or optical interference surface profiling.

The textured surface may be formed by a variety of methods such as wetetching, dry etching, masking and etching, photolithography, and thelike. In some embodiments, the textured surface may be formed bychemical etching at least one surface of the substrate. Chemical etchingmay include applying a mask on selected portions of the surface andremoving the exposed portions of the surface by etching sand blasting orgrinding. In some embodiments, the mask may be formed by formingprecipitates on the surface. In other embodiments, the masking may beachieved by polymer masking, polymer particle masking, or ink-jetting amask, or may utilize a mask formed by photolithography or nanoimprintlithography, a phase-separating polymer mask, a soluble (organic orinorganic) phase embedded in an insoluble polymer mask, an insolublepolymer mask including particles embedded therein or a combinationthereof. Where etching is used, the etchants may comprise hydrofluoricacid or hydroxide material such as KOH or NaOH plus chelating agents.Hydrofluoric acid may be combined with other acids such as hydrochloric,sulfuric, acetic, or nitric acids, where minimizing the formation ofprecipitate formation is desired and/or where etching the surface of thesubstrate without changing the resulting surface composition is desired.In some embodiments, enclosures with a textured surface may be formedinto different shapes through polishing or hot-forming, which may beperformed either before or after the texturing process. In otherembodiments, an enclosure with a textured surface may be strengthened(as described below) after the textured surface is formed.

In one or more embodiments, the textured surface may be formed by addingfeatures to the surface of the substrate (especially in the case oforganic substrates). The features may include particles that areattached or bonded to the surface. In some embodiments, an adhesive maybe utilized to bond the particles to the surface. In other embodiments,the particles may be directly bonded to the surface. The particles mayhave an average major dimension in the range from 5 micrometers to about100 micrometers. The particles may be formed from the same material asthe substrate, or from a different material.

In one or more embodiments, the textured surface may include a coatingor coatings disposed on the textured surface, forming a coated texturedsurface. The coatings may be placed on top of the textured surface toprovide various functionalities. The coatings may include ink coatings,hard coatings, scratch-resistant coatings, low-friction coatings,high-friction coatings, oleophobic coatings, oleophilic coatings,hydrophobic coatings, hydrophilic coatings, coatings that exhibithydrophobicity and oleophobicity, reflective or anti-reflectivecoatings, or easy-to-clean coatings that show a combination of thesefunctions. The specific choice of coating depends on the desired uses ofthe electronic device, as well as design considerations. In some casesthe coatings may be relatively thick (e.g., in the range from about 1micrometer to about 3 micrometers, in the case of scratch-resistantcoatings), or may be relatively thin (e.g., in the range from about 0.5nanometers to about 50 nanometers, in the case of hydrophobicity andoleophobicity coatings, oleophobic coatings or oleophilic coatings).

In one or more embodiments, the textured surface imparts oleophilicityor hydrophobicity and oleophobicity to the substrate surface (without acoating disposed thereon) and thus forms a tactile surface that exhibitsanti-fingerprint properties or performance. In one or more embodiments,the textured surface enhances or promotes the oleophilicity orhydrophobicity and oleophobicity of certain substrate, such as glass andsome glass ceramic substrates. Without being bound by theory, it isbelieved that this enhanced oleophilicity or hydrophobicity andoleophobicity provides anti-fingerprint functionality because thevisibility of a fingerprint on a surface is largely determined by lightscattering, and in turn this light scattering is largely dependent onthe size of the scattering oil droplets left behind by a fingerprint.Oleophobic surfaces or hydrophobic and oleophobic surfaces, such asthose commonly used in non-textured display cover substrates, tend tocreate a large number of fingerprint droplets having an average longestcross-sectional dimension of 2 micrometers or less, as measured byoptical or other known means for measuring such droplets. Such dropletsare highly light scattering droplets and thus increase the visibility ofthe fingerprint. In contrast, oleophilic surfaces tend to create smearsor very broad droplets that are larger than 5 micrometers in size, withmuch reduced light scattering, particularly at scattering angles greaterthan about 5 degrees away from the specular reflection angle.Accordingly, it is believed a textured surface exhibiting oleophilicityprovides improved anti-fingerprint performance.

In some embodiments, the textured surface includes a coating. In one ormore embodiments, the coating is a low-friction coating or a coatingthat reduces COF of the textured surface. In one or more embodiments,the coating is also at least somewhat oleophilic, to form an oleophiliccoated textured surface or a hydrophobic and oleophobic coated texturedsurface. Such coated textured surfaces can provide a smooth glidingsurface for fingers. In one or more embodiments, such coated texturedsurfaces can provide some spreading of oil droplets to further minimizelight scattering. In some examples, coated textured surfaces including alow-friction coating exhibit a kinetic coefficient of friction (COF) ofless than 0.3, when measured by the COF Test Method (described herein).In some examples, coated textured surfaces including a low-frictioncoating exhibit a static COF of less than 0.3, as measured by the COFTest Method. Examples of low-friction coatings may include glass surfacereactive porous alkyl siloxanes (e.g., methyl siloxane, ethyl siloxane,propyl siloxane, and the like), porous phenyl siloxanes, porous alkylsilanes, inorganic coatings (such as alumina, titania, zirconia,aluminum titanium nitride) or combinations thereof. In one or morealternative embodiments, the textured surface may include ahigh-friction coating forming a coated textured surface. Examples ofsuch high-friction coatings include alkyl siloxanes (e.g., methylsiloxane, ethyl siloxane, propyl siloxane, and the like), phenylsiloxanes, alkyl silanes and other similar materials.

As used herein, the COF Test Method is used to measure static andkinetic COF using a coefficient of friction instrument (COF-1000)supplied by ChemInstruments, Inc. of Fairfield, Ohio, coupled with datamanagement software. Measurements were obtained using a 200 g or 500 gload applied at 12 inches/minute. Unless specified otherwise, thesamples measured had dimensions of 65 mm by 135 mm, and were attached tothe moving substrate by means of a clip. The test material included amicrofiber cloth supplied by Photodon, LLC of Traverse City, Mich. underthe trade name 382ZZ and having zigzag edges with dimensions 7 inches by6 inches. The cloth comprises 80% polyester, 20% nylon and has a densityof 260 grams/m². Cloth was cut into squares having dimensions of 2inches by 2 inches and affixed to a test glass substrate by double sidedtape. The test apparatus is illustrated in FIG. 5, which shows thesubstrate 212 (with the tactile surface) be tested affixed to a movingsubstrate 210. The cloth 222 is shown affixed to a test glass substrate220. The cloth 222 and test glass substrate 220 are coupled to thecoefficient of friction instrument 300. The tactile surface faces thecloth 222 so the COF of the surface can be measured.

In one or more embodiments, the tactile surface is substantially free ofa coating (e.g., free of an oleophilic coating) and may exhibit a staticor kinetic COF of less than 0.5, when measured under the COF Test Methodusing a load of 500 g. In some embodiments, the tactile surface issubstantially free of a coating (e.g., free of an oleophilic coating)and may exhibit a static or kinetic COF of in the range from about 0.05to about 0.4, 0.05 to about 0.3, 0.05 to about 0.2, 0.1 to less than0.5, 0.15 to less than 0.5, or 0.2 to less than 0.5. In one or moreembodiments, the tactile surface may include a low-friction coating andexhibits the static or kinetic COF disclosed herein.

In some instances, a bare tactile surface (without any coating) exhibitsan oleophilicity that decreases with use, as oils, dirt and fingerprintsaccumulate on the textured surface. In some embodiments, the texturedsurface includes a coating that maintains a certain degree ofoleophilicity. Such coatings can include TiO₂, which is believed to be a“self-cleaning” material after exposure to ultraviolet light.Specifically, TiO₂ coatings can chemically break down absorbed oils anddirt after exposure to ultraviolet light or even sunlight throughphotocatalysis.

Enclosures according to one or more embodiments may be free of atextured surface but include a coating forming the anti-fingerprintsurface. Such coatings impart oleophilicity or hydrophobicity andoleophobicity to the surface.

In one or more embodiment, the tactile surface exhibits ananti-fingerprint functionality such that, after a wipe of a finger orother applicator containing oil or oleic acid, the surface includesdroplets that have an average major dimension of greater than about 2micrometers, greater than about 5 micrometers, or greater than about 10micrometers.

The visibility, based on brightness, may be calculated by the followingequation, where the subscript 1 indicates an area including afingerprint and subscript 2 indicates an area without a fingerprint: theabsolute value of the difference (brightness₁−brightness₂), divided bythe sum (brightness₁+brightness₂). In some embodiments, the texturesurface exhibits a visibility of less than about 0.99, less than about0.95, less than about 0.8, less than about 0.7, less than about 0.6,less than 0.5, less than 0.25, less than 0.2, less than 0.1, less than0.05 at certain selected angles.

Enclosure

In one or more embodiments, the enclosure may be transparent,translucent, or opaque. In embodiments of a transparent enclosure, suchenclosures may exhibit an average total transmittance (taking intoaccount both the interior and exterior surface of the enclosure of about80% or greater, 85% or greater, 90% or greater, or 95% or greater, overthe visible spectrum. In some instances, the enclosure may exhibit anaverage total transmittance in the range from about 80% to about 96%,from about 80% to about 94%, or from about 80% to about 92%, over thevisible spectrum. As used herein, the term “transmittance” is defined asthe percentage of incident optical power within a given wavelength rangetransmitted through a material (e.g., the enclosure or portionsthereof). Transmittance is measured using a specific line width. In oneor more embodiments, the spectral resolution of the characterization ofthe transmittance is less than 5 nm or 0.02 eV. As used herein, the“visible spectrum” includes the wavelength range from about 420 nm toabout 700 nm.

In one or more embodiments, the enclosure also exhibits 4-point bendstrength, stiffness or Young's Modulus, hardness, crack indentationthreshold, thermal conductivity, and strength (in terms of depth ofcompressive layer (DOC), surface compressive stress and centraltension).

In one or more embodiments, the enclosure may include the substratedescribed herein. The substrate may form the entire enclosure or aportion of the enclosure.

In one or more embodiments, the enclosure permits transmission ofwireless data transmission or wireless charging energy. In someembodiments, the enclosure exhibits both radio and microwave frequencytransparency, as defined by a loss tangent of less than 0.03 and at afrequency range of between 15 MHz to 3.0 GHz. In another exemplaryembodiment the article, particularly the electronic device enclosureexhibits radio and microwave frequency transparency, as defined by aloss tangent of less than 0.015 over the frequency range of between 500MHz to 3.0 GHz. This radio and microwave frequency transparency featureis especially important for wireless hand held devices that includeantennas internal to the enclosure. This radio and microwavetransparency allows the wireless signals to pass through the enclosureand in some cases enhances these transmissions. Furthermore, it may alsobe desirable to be transparent in the infrared to allow wireless opticalcommunication between electronic devices; specifically an infra-redtransparency of greater than 80% at wavelengths in the range from about750 to about 2000 nm. In other embodiments, the enclosure is permitstransmission of magnetic fields and/or inductive fields.

The enclosure may also exhibit various mechanical attributes for usewith portable electronic devices. For example, some embodiments of theenclosure exhibit any one or more of: a fracture toughness of greaterthan 0.6 MPa·m^(1/2), a 4-point bend strength of greater than 350 MPa, aVickers hardness of at least 600 kgf/mm² and a Vickers median/radialcrack initiation threshold of at least 5 kgf, a Young's Modulus in therange from about 50 GPa to about 100 GPa, a thermal conductivity of lessthan 2.0 W/m° C. In some embodiments, the enclosure exhibits acombination of fracture toughness in excess of 0.6 MPa·m^(1/2), theabove-recited Vickers hardness/indentation threshold, and 4-point bendstrength. In one or more embodiments, the enclosure exhibits a fracturetoughness of greater than 0.70 MPa·m^(1/2), and an 4-point bend strengthof greater than 475 MPa or greater than 525 MPa and a Young's Modulus inthe range from about 50 GPa to about 75 GPa.

The enclosure described herein may deform upon indentation primarily bydensification rather than by shear faulting. In some embodiments, theenclosure is free of subsurface faulting and radial cracks upondeformation. In some embodiments, such as when the substrate utilized isstrengthened, the resulting enclosure is more resistant to crackinitiation by shear faulting. In one embodiment, the enclosure comprisesa strengthened substrate and exhibits a Vickers median/radial crackinitiation threshold of at least 5 kilogram force (kgf). In a secondembodiment, the enclosure has a Vickers median/radial crack initiationthreshold of at least about 10 kgf or at least about 30 kgf.

In one or more embodiments, the enclosure exhibits a thermalconductivity of less than 2 W/m° C., and thus, remains cool to the toucheven in high operating temperatures (e.g., temperatures approaching 100°C.). In some embodiments, the enclosure exhibits a thermal conductivityof less than 1.5 W/m° C. For comparison, ceramics such as alumina mayexhibit thermal conductivities as high as 29 W/m° C.

EXAMPLES

Various embodiments will be further clarified by the following examples.

Example 1

Alkali aluminosilicate glass substrates (having a sheet form a and whichwere not strengthened) having a nominal composition of 57.5 mol % SiO₂,16.5 mol % Al₂O₃, 16 mol % Na₂O, 2.8 mol % MgO and 6.5 mol % P₂O₅, and athickness of 0.7 mm were cleaned by immersing in detergent solution andapplying ultrasonic agitation to the detergent solution. The cleanedsubstrates were then removed from the detergent solution and thenstatically etched by applying an etchant including 6 weight percenthydrofluoric acid (HF) and 15 weight percent NH₄F for 8 minutes (StepA). The etched substrates were then rinsed and thoroughly with DI water.The etched substrates were then were dipped in a solution of 5 wt % HFfor the durations indicated in Table 1 to achieve the desired haze level(Step B). After the second etching step, the glass substrates werecleaned by DI water to remove acid residue and any etch byproduct.Resulting substrates (Examples 1A-1K) included textured surface on bothmajor surfaces and both minor surfaces. One glass substrate was notsubjected to any etching steps (Comparative Example 1L). Thetransmittance haze, transmittance, final substrate thickness, longestcross-sectional dimension of the largest feature, and surface roughness(Ra) were measured on the major surfaces of resulting Examples 1A-1K andComparative Example 1L.

TABLE 1 Properties for Examples 1A-1K and Comparative Example 1L, basedon etching times. Approximate longest cross- Final sectional substratedimension of Surface Etching Time (min) Haze Transmittance thicknesslargest feature roughness Ra Ex. Step A Step B (%) (%) (mm)(micrometers) (nm) 1A 8 0 109 82.8 0.699 n/a 1216 1B 8 2 104 90.8 0.67618.3 1C 8 3.1 101 90.7 0.665 22.1 998 1D 8 4.5 95 90.5 0.652 25.4 1E 85.8 91 90.9 0.646 28.8 1F 8 7.1 88 90.9 0.633 30.6 1G 8 8.4 82 91.10.618 31 773 1H 8 9.8 78 91.3 0.605 34.3 1I 8 11.1 70 91.4 0.592 35.5 1J8 13.7 60 92.3 0.571 39 1K 8 16.4 50 92.8 0.552 47.33 605 Comp. 1L n/an/a 0 93.0 0.705 n/a

FIG. 6 shows an optical microscope image of Example 1K taken at 200×magnification. The largest lateral features had a longestcross-sectional dimension of about 44.452 micrometers and 47.330micrometers (a 50 micrometer scale is included for reference).

Example 2

Alkali aluminosilicate glass substrates (having a sheet form a and whichwere not strengthened) having the same nominal composition as Example 1and identical thicknesses were cleaned by immersing in detergentsolution and applying ultrasonic agitation to the detergent solution.The cleaned substrates were then removed from the detergent solution. Asingle major surface was coated with an etch-resistant film and thenstatically etched by applying an etchant including 2 weight percent or 6weight percent hydrofluoric acid (HF) and 15 weight percent or 30 weightpercent NH₄F for 8 minutes (Step C). The etched substrates were thenrinsed and thoroughly with DI water. The etched substrates were thenwere dipped in a solution of 5 wt % HF for the durations indicated inTable 2 to achieve the desired haze level (Step D). After the secondetching step, the glass substrates were cleaned by DI water and theacid-resistant film is removed. Resulting Examples 2A-2E included atextured surface on a single major surface, and both minor surfaces. Theopposing major surface was free of a textured surface. The transmittancehaze, DOI, Gloss at 60°, surface roughness (Ra), and average longestcross-sectional dimension of the features, were measured on the texturedmajor surface of resulting Examples 2A-2E.

TABLE 2 Properties for Examples 2A-2E, based on etching times. Averagelongest cross-sectional Gloss Surface dimension of the Etching Time(min) Haze DOI at 60° roughness Ra features Ex. Step A Step B (%) (%)(%) (nm) (μm) 2A 8 (3 wt % 10.6 12.8 92.4 63.1 227 21 HF/30 wt % NH₄F)2B 8 (6 wt % 16.4 33.2 1.1 22.6 583 37 HF/15 wt % NH₄F) 2C 8 (6 wt % 1049.5 0.8 16.4 610 34 HF/15 wt % NH₄F) 2D 8 (6 wt % 8.4 61.5 1.0 14.8 76032 HF/15 wt % NH₄F) 2E 8 (6 wt % 2 97.6 0.0 11.9 1113 n/a HF/15 wt %NH₄F)

The static COF of Examples 2A-2E was measured (as described herein)before and after coating with an easy-to-clean coating, as shown inTable 3. The easy-to-clean coating (imparting hydrophobicity andoleophobicity to the surface) included an alkoxysilane functionalperfluoropolyether (PFPE) hybrid polymer supplied by Dow CorningCorporation of Midland, Mich., under the trade name Dow Corning 2634,and hydrofluoroether solvent supplied by The 3M Company of Minneapolis,Minn., under the trade name 3™ Novec™ 7200 Engineered Fluid. Theeasy-to-clean coating was prepared by combining 4.2 mL of thealkoxysilane functional perfluoropolyether (PFPE) hybrid polymer and 1 Lof the hydrofluorether solvent and sprayed using a spray applicatorsupplied by Nordson ASYMTEK of Carlsbad, Calif., under the trademarkSC-300 Swirl Coat®, using a valve supplied by Nordson EFD of EastProvidence, R.I., under the trade name MM781-SYS MicroMark. The coatingwas applied using a 2.5 mL/minute flow rate, at 30 psi air pressure, 20inch/minute velocity for 2 hours in an environment at 50° C. and 50%relative humidity. Any excess applied easy-to-clean coating was thenwiped off using an isopropyl alcohol wipe.

Ex. COF without coating COF after coating Haze 2A 0.28 0.09 12% 2B 0.240.11 32% 2C 0.25 0.13 51% 2D 0.28 0.20 65% 2E 0.48 0.43 99%

FIGS. 7A-7E show the impact of easy-to-clean (ETC) coating oncoefficient of friction (COF) for the different haze and roughnesslevels of Examples 2A-2E. The COF was measured five times on the sameExample using a 500 g load. As shown in FIGS. 7A-7E, the ETC coating wasmore effective in reducing the COF when the surface roughness (and haze)is low, and became less effective as surface roughness (and haze)increased.

FIG. 8 shows the static COF of Examples 2B-2E as a function oftransmittance haze. The results showed that the application of an ETCcoating was more effective in reducing the COF when the surfaceroughness (and haze) is low, and became less effective as surfaceroughness (and haze) increased.

Example 3

Glass substrates having the same nominal composition as Example 1 andidentical shape and thickness were sandblasted at a pressure of 20 psiwith SiC particles to create a textured surface exhibiting hightransmittance haze and roughness. The substrates were then rinsed withDI water to remove any debris from sandblasting. The substrates wherethen chemically polished using a 5 weight percent HF solution forvarious times (as indicated in Table 4) and then rinsed in DI wateragain. Resulting Examples 3A-3D included a textured surface on a singlemajor surface. The opposing major surface was free of a texturedsurface. The transmittance haze, and surface roughness (Ra), weremeasured on the textured surface of resulting Examples 3A-3D.

TABLE 4 Properties for Examples 3A-3D, based on chemical polishing time.Transmittance Surface Chemical Polishing time Haze (%) Roughness (nm) in5 wt % HF (min) 90+% 1460 0 90+% 1941 2 90+% 2405 4 90+% 2367 8

Various modifications and variations can be made to the materials,methods, and articles described herein. Other aspects of the materials,methods, and articles described herein will be apparent fromconsideration of the specification and practice of the materials,methods, and articles disclosed herein. It is intended that thespecification and examples be considered as exemplary. Exemplaryembodiments include the following.

Embodiment 1. An electronic device comprising: an enclosure, andelectrical components disposed at least partially inside the enclosure,the electronic components comprising a controller, a memory, and adisplay, wherein the enclosure comprises a substrate, and the substratecomprises

an average transmittance of about 80% or greater over the visiblespectrum;

a static coefficient of friction less than about 0.3,

a surface roughness Ra of about 500 nm or greater, and

either one or both

-   -   a transmission haze greater than about 60%, and    -   a reflection haze at either 2 degrees from specular or 5 degrees        from    -   specular greater than 60%.

Embodiment 2. The electronic device of embodiment 1, wherein thesubstrate comprises an amorphous substrate or a crystalline substrate.

Embodiment 3. The electronic device of embodiment 2, wherein thesubstrate is amorphous and comprises any one of a soda lime glass, analkali aluminosilicate glass, an alkali containing borosilicate glassand an alkali aluminoborosilicate glass.

Embodiment 4. The electronic device of embodiment 2 or embodiment 3,wherein the substrate is amorphous and is strengthened.

Embodiment 5. The electronic device enclosure of any one of embodiments2-4, wherein the substrate is amorphous and further comprises any one ormore of

a compressive surface layer having a depth of layer (DOC) greater thanor equal to 20 μm,

a surface compressive stress greater than 400 MPa, and

a central tension of more than 20 MPa.

Embodiment 6. The electronic device enclosure of embodiment 2, whereinthe substrate is crystalline and comprises a strengthened glass ceramicsubstrate, a non-strengthened glass-ceramic, or a single crystalsubstrates.

Embodiment 7. The electronic device of any one of the precedingembodiments, wherein the substrate comprises an ink layer disposed amajor surface of the substrate.

Embodiment 8. The electronic device of any one of the precedingembodiments, wherein the substrate comprises a colored glass.

Embodiment 9. The electronic device of any one of the precedingembodiments, wherein the transmission haze is greater than about 90%.

Embodiment 10. The electronic device of any one of the precedingembodiments, wherein the reflection haze at either 2 degrees fromspecular or 5 degrees from specular is greater than about 90%, asmeasured by ASTM E430.

Embodiment 11. The electronic device of any one of the precedingembodiments, further comprising a layer of hydrophobic material,oleophobic material or hydrophobic and oleophobic material.

Embodiment 12. The electronic device of any one of the precedingembodiments, wherein the Ra surface roughness is about 700 nm orgreater.

Embodiment 13. The electronic device of any one of the precedingembodiments, wherein the substrate further comprises a tactile surface,the tactile surface comprising a plurality of features having a longestcross-sectional dimension in the range from about 10 micrometers toabout 50 micrometers.

Embodiment 14. The electronic device of embodiment 13, wherein theplurality of features comprise an average longest cross-sectionaldimension is about 2 times or greater than the longest cross-sectionaldimension.

Embodiment 15. The electronic device of embodiment 13, wherein theplurality of features comprises an average longest cross-sectionaldimension is about 2 times or less than the longest cross-sectionaldimension.

Embodiment 16. The electronic device of any one of the precedingembodiments, further comprising an electronic device selected from amobile phone, a tablet, a laptop, and a media player.

Embodiment 17. A substrate comprising:

first and second opposing major surfaces;

first and second opposing minor surfaces;

a tactile surface disposed on the first major surface, the tactilesurface comprising a plurality of features having a longestcross-sectional dimension in the range from about 10 micrometers toabout 50 micrometers.

wherein the substrate comprises:

an average transmittance of about 80% or greater over the visiblespectrum;

a coefficient of friction less than about 0.3, and

a surface roughness Ra of about 500 nm or greater,

either one or both

-   -   a transmission haze greater than about 60%, and    -   a reflection haze at either 2 degrees from specular or 5 degrees        from    -   specular greater than 60%.

Embodiment 18. The substrate of embodiment 17, wherein the plurality offeatures comprises an average longest cross-sectional dimension greaterthan or equal to about 2 times the longest cross-sectional dimension.

Embodiment 19. The substrate of embodiment 17, wherein the plurality offeatures comprises an average longest cross-sectional dimension lessthan or equal to about 2 times than the longest cross-sectionaldimension.

Embodiment 20. The substrate of any one of embodiments 17-19, whereinthe substrate comprises an amorphous substrate or a crystallinesubstrate.

We claim:
 1. Method of making an electronic device comprising: etching asubstrate to provide the substrate with an average transmittance ofabout 80% or greater over the visible spectrum; a static coefficient offriction less than about 0.3, a surface roughness Ra of about 500 nm orgreater, and either one or both a transmission haze greater than about60%, and a reflection haze at either 2 degrees from specular or 5degrees from specular greater than 60%; assembling the substrate in anenclosure; and disposing electrical components at least partially insidethe enclosure, the electronic components comprising a controller, amemory, and a display.
 2. The method of claim 1, wherein the substratecomprises an amorphous substrate or a crystalline substrate.
 3. Themethod of claim 2, wherein the substrate is amorphous and comprises anyone of a soda lime glass, an alkali aluminosilicate glass, an alkalicontaining borosilicate glass and an alkali aluminoborosilicate glass.4. The method of claim 2, wherein the substrate is amorphous and isstrengthened.
 5. The method of claim 2, wherein the substrate isamorphous and further comprises any one or more of a compressive surfacelayer having a depth of layer (DOC) greater than or equal to 20 μm, asurface compressive stress greater than 400 MPa, and a central tensionof more than 20 MPa.
 6. The method of claim 2, wherein the substrate iscrystalline and comprises a strengthened glass ceramic substrate, anon-strengthened glass-ceramic, or a single crystal structure.
 7. Themethod of claim 1, wherein the substrate comprises an ink layer disposeda major surface of the substrate.
 8. The method of claim 1, wherein thesubstrate comprises a colored glass.
 9. The method of claim 1, whereinthe transmission haze is greater than about 90%.
 10. The method of claim1, wherein the reflection haze at either 2 degrees from specular or 5degrees from specular is greater than about 90%, as measured by atransparency meter.
 11. The method of claim 1, further comprising alayer of hydrophobic material, oleophobic material or hydrophobic andoleophobic material.
 12. The method of claim 1, wherein the Ra surfaceroughness is about 700 nm or greater.
 13. The method of claim 1, whereinthe substrate further comprises a tactile surface, the tactile surfacecomprising a plurality of features having a longest cross-sectionaldimension in the range from about 10 micrometers to about 50micrometers.
 14. The method of claim 13, wherein the plurality offeatures comprise an average longest cross-sectional dimension is about2 times or greater than the longest cross-sectional dimension.
 15. Themethod of claim 13, wherein the plurality of features comprises anaverage longest cross-sectional dimension is about 2 times or less thanthe longest cross-sectional dimension.
 16. The method of claim 1,wherein the electronic device is selected from a mobile phone, a tablet,a laptop, and a media player.